In recent years the number of wireless networks has increased significantly. Wireless connectivity enables users to have access to other users, local area networks (LANs) and wide area networks (WANs), including the Internet, without requiring the user to remain at a single location. Moreover, the user's mobility is generally not restricted within the coverage area of the wireless network.
Wireless connectivity is not without disadvantages. Information transmitted in a wireless network can be intercepted by anyone in the range of the user that has a wireless receiver. Various types of security solutions have been developed to address these security concerns. One solution, virtual private networks (VPNs), provides security to wired and wireless networks. A VPN connects network resources through a secure protocol tunnel so that resources on separate networks seem to share a common private backbone. VPNs can be used, for example, to enable an employee to connect to an office LAN via an insecure home Internet connection or to permit a salesperson to access a corporate LAN while on travel. Advantageously, users realize the same confidentiality provided by private networks although the tunnel may utilize a public network.
Security is achieved, for example, using Internet Protocol security (IPSec). IPSec is a security architecture for Internet protocol (IP) communication that is based on a set of protocols developed by the Internet Engineering Task Force (IETF) for the secure exchange of packets at the IP layer. IPSec provides security by enabling a system to select required security protocols, determine one or more algorithms to for implementing security, and manage the use of cryptographic keys. The sending and receiving devices typically share a public key which is handled through an Internet Security Association and Key Management Protocol (ISAKMP).
A security association (SA) is a security-protocol-specific set of parameters that defines the services and mechanisms used to protect traffic at a security protocol location. These parameters typically include algorithm identifiers, modes, cryptographic keys, and the like. SAs are generally referred to by their associated security protocols (e.g., ISAKMP SA).
Today, IPSec VPN users are “anchored” to a specific VPN server or VPN cluster. Consequently, the mobility of each user is limited according to the reachability of its VPN server/cluster. As the user roams, some networks may become unreachable while other networks may become reachable. If a mobile user moves outside a private network and loses connectivity, a new IPSec connection may need to be established with a different VPN server or cluster. To overcome this limitation, the wireless device of the mobile user can be registered with a gateway VPN server at the edge of the private network and a public network, instead of a VPN server inside the private network. The gateway VPN server is reachable from the public network thus enabling seamless roaming when the mobile user transitions between the private and public networks. However, this solution can result in “tromboning” traffic within the private network as described in more detail below.
VPN users can also be affected by changes in server loads. A VPN user anchored to a specific VPN server can experience performance degradation if the load of that server increases during the VPN session. Current load-balancing algorithms for servers only act upon new VPN session requests to distribute server loads.
What is needed is a method that overcomes the above-described problems for VPN users. The present invention satisfies this need and provides additional advantages.